High sensitivity photonic time-stretch electro-optic sampling of terahertz pulses
Single-shot recording of terahertz electric signals has recently become possible at high repetition rates, by using thephotonic time-stretchelectro-optic sampling (EOS) technique. However the moderate sensitivity of time-stretch EOS is still a strong limit for a range of applications. Here we present a variant enabling to increase the sensitivity ofphotonic time-stretch for free-propagating THz signals. The ellipticity of the laser probe is enhanced by adding a set of Brewster plates, as proposed by Ahmedet al. [Rev. Sci. Instrum.85, 013114 (2014)] in a different context. The method is tested using the high repetition rate...
Source: Review of Scientific Instruments - October 18, 2016 Category: Physics Authors: C. Szwaj, C. Evain, M. Le Parquier, P. Roy, L. Manceron, J.-B. Brubach, M.-A. Tordeux and S. Bielawski Source Type: research
High performance charge-state resolving ion energy analyzer optimized for intense laser studies on low-density cluster targets
We report on a versatile ionanalyzer which is capable to resolve ioncharge states and energies with a resolution of E/ ΔE = 100 at 75 keV/nucleon.Charge states are identified by their characteristic deflection in amagnetic field, whereas the ion energies are independently determined by atime-of-flight measurement. To monitor the signals a delay-linedetector is used which records ion impact positions and times in each laser shot. Compared to conventional Thomson parabola spectrometers our instrument provides a low background measurement, hence a superior dynamic range. Further features are an improved energy resolution and...
Source: Review of Scientific Instruments - October 18, 2016 Category: Physics Authors: D. Komar, K.-H. Meiwes-Broer and J. Tiggesb äumker Source Type: research
2D spatial profile measurements of potential fluctuation with heavy ion beam probe on the Large Helical Device
Two-dimensional spatial profiles of potentialfluctuation weremeasured with theheavy ion beam probe (HIBP) in theLarge Helical Device(LHD). For 2D spatial profilemeasurements, the probebeam energy has to be changed, which requires the adjustment of many deflectors in thebeam transport line to optimize thebeam trajectory, since the transport line of LHD-HIBP system is long. The automaticbeam adjustment system was developed, which allows us to adjust thebeam trajectory easily. By analyzingcoherence between potentialfluctuation and magnetic probe signal, the noise level of the mode power spectrum of the potentialfluctuation ca...
Source: Review of Scientific Instruments - October 18, 2016 Category: Physics Authors: A. Shimizu, T. Ido, M. Nishiura, S. Kato, K. Ogawa, H. Takahashi, H. Igami, Y. Yoshimura, S. Kubo and T. Shimozuma Source Type: research
Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas
Spectroscopic techniques in the visible range are often used inplasma experiments tomeasure B-field inducedZeeman splitting,electron densities via Stark broadening, andtemperatures fromDoppler broadening. However, whenelectron densities andtemperatures are sufficiently high, the broadening of the Stark andDoppler components can dominate theemission spectra and obscure theZeeman component. In this research, we are developing a time-resolved multi-axial technique formeasuring theZeeman, Stark, andDoppler broadened line emission of dense magnetized plasmas for Z-pinch and DensePlasma Focus (DPF) accelerators. The line emissio...
Source: Review of Scientific Instruments - October 18, 2016 Category: Physics Authors: E. C. Dutra, J. A. Koch, R. Presura, W. A. Angermeier, T. Darling, S. Haque, R. C. Mancini and A. M. Covington Source Type: research
New Products
(Source: Review of Scientific Instruments)
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: Andreas Mandelis Source Type: research
Note: 3D printed spheroid for uniform magnetic field generation
This article is focused on a novel and practical production method for a uniformmagnetic field generator. The method involves building of asurfacecoil template using a desktop3D printer and winding of a conducting wire onto thestructure usingsurface grooves as a guide. Groove pattern was based on the parametric spheroidal helicalcoil formula. Thecoil was driven by a current source and themagnetic field inside wasmeasured using a Hall probe placed into the holes on the printedstructure. Themeasurements are found to be in good agreement with ourfinite element analysis results and indicate a fairly uniform field inside. (Sour...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: Y. Öztürk and B. Aktaş Source Type: research
A voltage-division-type low-jitter self-triggered repetition-rate switch
A voltage-division-type (V/N) low-jitter self-triggered multi-stage switch is put forward. It comprises of a triggered corona gap, several quasi-uniform-field gaps, and an inversioninductor. When the corona gap is in the stage of self-breakdown, the multi-stage gaps are triggered and the switch is closed via an over-voltage. This type of V/N switch has the advantage of compact structure since the auxiliary components like the gas-blowing system and the triggered system are eliminated from the whole system. It also has advantages such as low breakdown jitter and highenergy efficiency. The dependence of the self-triggered vo...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: Jian-cang Su, Bo Zeng, Peng-cheng Gao, Rui Li, Xiao-long Wu and Liang Zhao Source Type: research
Injection barrel with a tapered structure for a low speed and small size cryogenic hydrogen pellet in medium-sized plasma fusion devices
An injection barrel was designed andfabricated for a small size 0.8 mmcryogenic pellet with a low speed of 200-300 m/s in medium-sizedplasmafusion devices. Pellet injection withpneumatic acceleration was examined using a conventionalin situ technique. A tapered structure was applied in the downstream side of the injection barrel to satisfy the requirement of pellet speed reduction by expansion of the propellant gas. Shadowgraph and light gatemeasurements show that the intact pellets have speeds of 260 ± 30 m/s and a typical size of 1.1-1.2 mm. The pellet ablation code based on a neutral gas shielding model shows that the ...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: G. Motojima, R. Sakamoto, H. Okada, K. Nagasaki, H. Yamada, Y. Nakamura, S. Kado, S. Kobayashi, S. Konoshima, T. Minami, S. Ohshima, S. Yamamoto, T. Mizuuchi and T. Mutoh Source Type: research
Direct measurement of the Goos-H änchen shift using a scanning quadrant detector and a polarization maintaining fiber
High precisionmeasurements of opticalbeam shifts are important in various fields including sensing, atomic force microscopy, andmeasuringbeam shifts at interfaces. Sub-micron shifts are generallymeasured by indirect techniques such as weakmeasurements. We demonstrate a straightforward and robustmeasurement scheme for the shift, based on a scanning quadrantphotodiode (QPD) that is biased using a lownoise electronic circuit. The shift ismeasured with respect to a referencebeam that is co-propagating with the signalbeam. Thus, the shift of the signalbeam is readout directly as the difference between the x-intercepts of the QP...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: Venkata Jayasurya Yallapragada, Gajendra L. Mulay, Ch. N. Rao, Ajith P. Ravishankar and Venu Gopal Achanta Source Type: research
Infrared ion spectroscopy in a modified quadrupole ion trap mass spectrometer at the FELIX free electron laser laboratory
We report on modifications made to a Paul-type quadrupoleion trapmass spectrometer and discuss its application in infrared ionspectroscopy experiments. Main modifications involve optical access to the trapped ions and hardware and software coupling to a variety of infrared laser sources at the FELIX infraredfree electron laser laboratory. In comparison to previously described infrared ionspectroscopy experiments at the FELIX laboratory, we find significant improvements in efficiency and sensitivity. Effects of thetrapping conditions of the ions on the IR multiple photondissociationspectra are explored. Enhanced photo-disso...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: Jonathan Martens, Giel Berden, Christoph R. Gebhardt and Jos Oomens Source Type: research
Laser ultrasonics for bulk-density distribution measurement on green ceramic tiles
In this paper aLaser Ultrasonics (LUT) system is developed and applied tomeasure bulk density distribution of greenceramic tiles, which are porous materials with low heat conductivity. Bulk density of greenceramic bodies is a fundamental parameter to be kept under control in the industrial production ofceramic tiles. The LUT system proposed is based on a Nd:YAG pulsed laser for excitation and an air-coupled electro-capacitivetransducer for detection. The paper reports experimental apparent bulk-densitymeasurements on whiteceramic bodies after acalibration procedures. The performances observed are better than those previous...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: G. M. Revel, A. Cavuto and G. Pandarese Source Type: research
Publisher ’s Note: “Multi-energy x-ray detector calibration for Te and impurity density (nZ) measurements of MCF plasmas” [Rev. Sci. Instrum. 87, 11E320 (2016)]
(Source: Review of Scientific Instruments)
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: J. Maddox, N. Pablant, P. Efthimion, L. Delgado-Aparicio, K. W. Hill, M. Bitter, M. L. Reinke, M. Rissi, T. Donath, B. Luethi and B. Stratton Source Type: research
Ion temperature and toroidal rotation in JET ’s low torque plasmas
This paper reports on the procedure developed as the best method to provide an accurate and reliable estimation of the iontemperature Ti and the toroidal velocity vϕ fromCharge-eXchange Recombination Spectroscopy(CXRS) data from intrinsic rotation experiments at the Joint European Torus with thecarbon wall. The low impurity content observed in suchplasmas, resulting in low activeCXRS signal, alongside lowDoppler shifts makes the determination of Ti and vϕ particularly difficult. The beam modulation method will be discussed along with themeasures taken to increase photon statistics and minimise errors from the absolutecal...
Source: Review of Scientific Instruments - October 17, 2016 Category: Physics Authors: J. Bernardo, M. F. F. Nave, C. Giroud, S. Reyes Cortes, Jo ão P. S. Bizarro and JET Contributors Source Type: research
The reactor –activator for gas-jet deposition of diamond structures
This paper presents a new method of deposition ofdiamond anddiamond like structures by using the original reactor for activation of carbonaceous gas mixtures. One of the important characteristics of the described reactor is the power efficiency owing to low heat losses. The new method of gasflow formation opens new possibilities to get important trade-offs (wide range of background conditions and others). The principal possibility ofdiamond deposition is proved by experiments with theflow of hydrogen andmethane mixture intungsten resistively heating cylindrical channels. Electron microphotographs and Raman spectrum of depo...
Source: Review of Scientific Instruments - October 14, 2016 Category: Physics Authors: A. K. Rebrov, M. N. Andreev, T. T. B ’yadovskiy, K. V. Kubrak and I. B. Yudin Source Type: research
Hyperthermal molecular beam source using a non-diaphragm-type small shock tube
We have developed a hyperthermal molecular beamsource employing a non-diaphragm-type smallshock tube for gas –surface interaction studies. Unlike conventional shock-heated beamsources, the capability of repetitive beam generation without the need for replacing a diaphragm makes our beamsource suitable for scattering experiments, which require signal accumulation for a large number of beam pulses. The short duration ofshock heating alleviates the usual temperature limit due to the nozzle material, enabling the generation of a molecular beam with higher translationalenergy or that containing dissociated species. The shock-...
Source: Review of Scientific Instruments - October 13, 2016 Category: Physics Authors: Yuta Yoshimoto, Kenichi Osuka, Nobuya Miyoshi, Ikuya Kinefuchi, Shu Takagi and Yoichiro Matsumoto Source Type: research
